Just to close off this question for myself, anyway, I was having issues with scratches that would not clear after polishing, with hand-sanding with 1200 grit and mineral oil. I put a sheet of 1200 in my quarter-sheet Porter Cable sander, lubed well with the mineral oil and lightly wet sanded. did not make a mess, I was careful to keep it wet, and polishing out went very well, no scratches that I can see with 2X magnification, so I call it a success.

My son went out and bought some fine (2000-4000 grit) 3" hook-and-loop sanding disks, and borrowed my 3" Griot polisher to do some finish sanding on his car. He got very good results. I'm really tempted to do some experimenting with that. I'm going to do some testing with Brite Tone on some scrap and may give this a try. The foam padding on the backs of these disks is a bit "squishy", so obviously not good for level-sanding, but might be suitable for the finish sanding.

I've been using 600 grit open coat Fre-Cut 3M paper on the palm sander to level sand after spraying as a first step. It works really well, the pad on the 1/4 sheet sander is only 1/8" thick so creates level quite well. The sandpaper clears really easily by wiping on a towel, and lasts seemingly forever. I feel like I'm kind of getting a rhythm down for finishing now...

It's much less aggressive than a typical random orbital sander, which I use for shaping and rough finishing, and polishing with thick foam pads. It is the one recommended by Bob Benedetto for finish sanding. I find hand sanding to be too scratch-inducing compared to the 1/4 sheet sander, which uses tiny circles and leaves almost no long scratches that catch the eye. I'm really quite pleased I tried it. I found it extremely controllable in the recurve area, up to the edges, and cleaning up and blending a few runs. Although why I can spray 10 coats without runs and get runs on the 11th and final coat I have not yet figured out.